What are the Boston suspect's legal rights?

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Suspect can't talk, the evidence can

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Decision not to immediately Mirandize Boston suspect has sparked debate

Officials only have to read rights to a suspect if they intend to use his statements at trial

Some legislators want the suspect declared an "enemy combatant"

Dzhokar Tsarnaev, 19, the primary suspect in Monday's bombings at the Boston Marathon, was taken into custody Friday night.

When Tsarnaev was captured, authorities indicated they did not intend to read him his Miranda rights, which include the right to remain silent, the right to an attorney regardless of financial circumstances and the warning that any statements can be used to aid his prosecution. It's an address made famous by countless TV police procedurals.

The decision not to "Mirandize" Tsarnaev has sparked debate among advocates, lawyers and legislators. What was the thinking behind the decision? What impact could it have on his case?

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Why give bombing suspect Miranda rights?

Law enforcement officials only have to Mirandize a suspect if they intend to use his statements at trial. In the Tsarnaev case, however, the federal government is invoking the public safety exception, a Justice Department official told CNN on condition of anonymity. It's a designation that allows investigators to question a suspect before apprising him of his rights when they believe there is an imminent public safety threat.

The public safety exception dates back to a 1984 case, New York v. Quarles. Its most recent interpretation dates back to a 2010 memo by the Obama Justice Department, and it was explained in a 2011 FBI bulletin.

"When police officers are confronted by a concern for public safety, Miranda warnings need not be provided prior to asking questions directed at neutralizing an imminent threat, and voluntary statements made in response to such narrowly tailored questions can be admitted at trial," the bulletin read.

What other reasons might there be for not reading a suspect's Miranda rights?

Some legislators, notably U.S. Sens. John McCain of Arizona and Lindsey Graham of South Carolina, want the suspect declared an "enemy combatant," a designation that allows a suspect to be questioned without a lawyer and without being informed of his Miranda rights. It applies to foreign nationals caught on an enemy battlefield, but such definitions have become murkier in the "war on terror."

If Tsarnaev, a naturalized American citizen, is given such a designation, he could be tried in federal court and face the death penalty, which Massachusetts does not have.

If a person knowingly and voluntarily waives these rights, then anything he says to authorities can be used against him as evidence at a criminal trial. With the public safety exception, the government is allowed to question a suspect without giving him his Miranda warnings and still use the statements at his criminal trial.

If he asks for his Miranda rights, do they have to be read to him?

No. Miranda only matters for statements made by the accused that prosecutors intend to use later at trial.

What if a suspect is unable to communicate?

Currently, reports indicate that Tsarnaev is unable to speak. However, it's not necessary to be able to speak; one can communicate in other ways.

But other variables are in play that could delay his arraignment: He must be of sound mind to understand the charges against him. If he gets an attorney before arraignment, his attorney could ask for a delay until he can properly communicate with his client. His attorney is also likely to request that any interrogation by law enforcement cease.